Adjustable foot rest



FIG. 1 is a top left perspective view, showing a leg in phantom lines, the phantom lines being for illustrative purposes only and forming no part of the claimed design;

FIG. 2 is a left side elevation view;

FIG. 3 is a right side elevation view;

FIG. 4 is a front elevation view;

FIG. 5 is a top plan view; and,

FIG. 6 is bottom plan view.

The rear is plain and unadorned. 

The ornamental design for an adjustable foot rest, as shown and described. 